Ans. is 'a' i.e Rt. Leg and perineum Paracentral lobule:On the medial surface of cerebral hemisphere, the U shaped gyrus around the end of the central sulcus is the paracentral lobule.Motor cortex is located in the precentral gyrus on the superolateral surface of the hemisphere and in the anterior part of the paracentral lobule.Stimulation in this area results in movements in the opposite half of the body.The body is represented upside down in this area.A look at the motor homunculus in Ganong will show that the leg and perineum are represented in the paracentral lobule.